IPTV (Internet Protocol Television) is a system where a digital television service is delivered using Internet Protocol over a network infrastructure, such as IP Multimedia Service (IMS), in lieu of traditional broadcast or cable delivery. One implementation of IPTV over IMS is defined in the European Telecommunications Standards Institute (ETSI) document ETSI TS 182 027 V2.0.0 (February 2008), titled “Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); IPTV Architecture; IPTV functions supported by the IMS subsystem,” incorporated herein by reference in its entirety. Section 7.3.1 of this document defines the IPTV user profile. An IPTV user profile includes information on Linear TV and Content on Demand services to which a user is subscribed, technical data such as characteristic of the user's IP Terminal Function (ITF) and supported quality definition (e.g., high definition), parental controls, Personal Video Recorder (PVR) information, language preferences, and other data. An IPTV user profile may include personal information such as hobbies and interests, which may for example be used to tailor advertising directed to the user.
An IP Terminal Function (ITF) is a device capable of rendering television content to one or more users, and interacting with at least an IMS network. An ITF may comprise, for example, a “set-top box,” having a network interface and outputting video and audio to a television monitor. As another example, an ITF may comprise a television including integral network interface circuits. When a user registers at an ITF, an IPTV Application Server (IPTV-AS) retrieves an IPTV user profile associated with the user from a Home Subscriber Server (HSS), and provides the IPTV user profile to the ITF. The ITF then implements access privileges and restrictions based on the IPTV user profile, such as allowing access to subscribed premium channels, blocking access to non-subscribed or restricted (e.g., adult) channels, and the like. The IPTV user profile may additionally include information, such as past viewing habits, hobbies, and the like, that further personalize the IPTV experience for the user.
Individuals often enjoy watching television together. Two or more users, each subscribing to IPTV services from the same IPTV Service Provider, may wish to access IPTV content over the same ITF. In conventional IPTV systems, the two users would have to register through the ITF in the alternative—that is, either one user or the other being registered at a time. This may be inconvenient. For example, if Bob's IPTV user profile includes access to live sporting events, and Alice's IPTV user profile includes access to a premium movie channel, for Bob and Alice to watch television together, switching between a game and a movie, would require them alternately registering and un-registering through the ITF, to access the different types of content.